Cover (The Chemistry of Engineering Materials

Cover
CHEMISTRY
FOR THE
ENGINEERS
BCHE 111 (2853) : BE 221 : CEE - BSCE

TABLE OF CONTENTS
THE CHEMISTRY OF ENGINEERING MATERIALS
o Basic Concepts of Crystal Structure
o Metals
o Polymers
o Engineered Nano-materials
THE CHEMISTRY OF THE ENVIRONMENT
o The Chemistry of the Environment
o The Chemistry of Water
o Soil Chemistry
ENERGY
o Electrochemical Energy
o Nuclear Chemistry
o Fuels
INTRODUCTION TO CHEMICAL SAFETY
REFERENCES

Cover
(The Chemistry of Engineering Materials)
THE CHEMISTRY OF
ENGINEERING
MATERIALS

The Chemistry of Engineering Materials
Engineering materials are materials that are used as raw materials for
any sort of construction or manufacturing in an organized way of engineering
application. Engineering material is part of inanimate matter, which is useful
to engineering to produce products according to the needs and demand of
the society.
Almost every substance known to man has found its way into
engineering workshop at some time or other. The easiest way to explain this is
through classifying. Engineering materials can be classified into two (2), the
Metals and Non-metals
The most convenient way to study the properties and uses of
engineering materials is to classify them as shown in the figure below.
Ferrous
Metals
Engineering Non-Ferrous
Materials
Natural Materials
Non-Metals
Synthetic Materials
Metals can be further classified as Ferrous metals and Non-ferrous metals.
Ferrous metals these are metals and alloys containing a high portion of
the element iron. They have small amount of other metals or elements
added, to give the required properties. Ferrous metals are magnetic and give
little resistance to corrosion. Ferrous metals are known for their hardness,
durability and tensile strength.

Types of ferrous metals are as follows:
Steel is an alloy of carbon and iron which constitute carbon up to 2.1%.
Pure iron is a soft metal and as the carbon content in it increases, the metal
becomes harder and tougher. Steels are divided into plain Carbon and Alloy
steels.
Carbon steels are grouped according to their carbon content from
low, medium and high carbon. Hardness, strength and often brittleness
increase with increasing carbon content. Impurities such as phosphorus or
sulfur will lower the ductility and malleability qualities of steel.
Alloy steel is steel that is alloyed with a variety if elements between 1%
and 50% by weight to alter its mechanical properties. The main advantages
of alloy steels are the ability to respond to heat treatment, improved
corrosion resistance, improved properties at high and low temperatures and
combination with high strength with good ductility.
Cast iron consists of more than 2% carbon. The high carbon content
makes them excellent materials to use for casting and at much lower
temperatures than those required to cast steel. Cast iron is brittle and easily
break through hammer.
White cast iron is produced if most of the carbon is combined
chemically with the iron, performed by rapidly cooling it within molds. It is very
hard and brittle, and used for machinery parts which are subjected to
excessive wear, such as crusher jaws and grinding mill balls and liners.
Grey cast iron the molten iron is cooled slowly, it causes the carbon to
disassociate from the iron and form into graphite. Grey cast iron is softer, with
good compressive strength, and is widely used for machinery bases and
supports.

Carbon Steel
Steel
Alloy Steel
Ferrous
Metals
White Cast Iron
Cast Iron
Grey Cast Iron
Non-ferrous metals these materials refer to the remaining metals known
to mankind. They do not contain iron, are not magnetic and usually more
resistant to corrosion than ferrous metals. Non-ferrous metals are also non-
magnetic, which make them suitable for many electrical and electronic
applications.
Types of non-ferrous metals are as follows:
Copper obtained from copper ore which is melted and then further
refined by electrolysis. It is commonly made into castings, wire, bars, plates,
tubes. The properties which copper desirable are its high electrical
conductivity, high heat conductivity, high corrosion resistance and high
ductility and toughness
Aluminum is produced by electrolysis of bauxite ore. Being only 1/3 as
heavy as iron or steel, its low density is one of the most valuable properties
aluminum. It is also an important material because of its good conduction of
electricity, excellent conduction of heat and high resistance to corrosion

Copper
Non Ferrous Metals
Aluminum
Non- Metals can be further classified as Synthetic materials and Natural
materials.
Synthetic materials Is a material which is not derived from living
organisms and contains no organically produced carbon.
Types of synthetic materials are as follows:
Plastics are a group of materials, either synthetic or naturally occurring
that may be shaped when soft and then hardened to retain the given shape.
Ceramics these are produced by making naturally occurring clays at
high temperatures after molding to shape. They are used for high-voltage
insulators and high-temperature resistant cutting tool tips.
Composites are combination of two or more different materials that
results in a superior or stronger product. The physical and chemical properties
of each if the constituent materials remain distinct in the new material.
Plastics
Synthetic Material Ceramics
Composites
Natural materials are any product or physical matter that comes from
plants, animals and ground, originally derived from living organisms. Minerals
and the metals that can be extracted from them are also considered to
belong into this category.

Types of natural materials are as follows:
Wood this is naturally occurring fibrous composites material used for the
manufacture of casting patterns
Rubber this is used for hydraulic and compressed air hoses and oil seals.
Naturally occurring latex is too soft for most engineering uses but it is widely
used for vehicle tires when it is compounded with carbon black.
Emery this is a widely used abrasive and is naturally occurring aluminum
oxide. Nowadays it is produced synthetically to maintain uniform quality and
performance.
Oils used as bearing lubricants, cutting fluids and fuels.
Silicon this is used as an alloying element and also for the manufacture of
semiconductor devices.
Wood
Rubber
Natural Materials Emery
Oils
Silicon
Crystal Structure
Crystal structure is a unique arrangement of atoms in a crystal. A crystal
structure is composed of a unit cell, a set of atoms arranged in a particular
way, which is periodically repeated in three dimensions on a lattice.
Lattice is an ordered array of points describing the arrangement of
particles that form a crystal.

Solids can be categories as Crystalline and Amorphous
Crystalline is a periodic arrangement of atoms; definite repetitive pattern.
Amorphous is a random arrangement of atoms.
Polymers
Polymers are giant molecules of high molecular weight, called
macromolecules, which is build up linking together of a large number of small
molecules, called monomers. The reaction by which the monomers combine
to form polymer is known as polymerization.
Polymerization is a chemical reaction in which two or more substances
combine together with or without evolution of anything like water, heat or
any other solvents to form a molecule of high molecular weight. The product
is called polymer and the starting material is called monomer.
On the basis of their occurrence in nature, polymers have been
classified in three types
Natural polymers the polymers which occur in nature are called natural
polymers also known as biopolymers. Examples of such polymers are natural
rubber, natural silk, starch, proteins, etc.
Semi synthetic polymer they are the chemically modified natural
polymers such as hydrogenated, natural rubber, cellulose nitrate, etc.
Synthetic polymers the polymer which has been synthesized in the
laboratory is known as synthetic polymer. These are also known as manmade
polymers. Examples of such polymers are polyvinyl alcohol, polyethylene,
polystyrene, etc

On the basis of thermal response, polymers can be classified into two
groups
Thermoplastic polymers they can be softened or plasticized repeatedly
on application of thermal energy, without much change in properties if
repeated with certain precautions. Examples of such polymers are nylons,
PVC, sealing wax, etc.
Thermosetting polymers soome polymers undergo certain chemical
changes on heating and convert themselves into an infusible mass. The
curing or setting process involves chemical reaction leading to further growth
and cross linking of the polymer chain molecules and producing giant
molecules. For example, diene rubbers, epoxy resins, etc.
Nanomaterials
Nanomaterials are
defined as a set of
substances where at least
one dimension is less than
approximately 100
nanometers. A nanometer
is one millionth of a
millimeter – approximately
100,000 times smaller than the diameter of a human hair.
Nanomaterials occur naturally, but of particular interest are
engineered nanomaterials, which are designed for, and already being used
in many commercial products and processes. They can be found in such
things as sunscreens, cosmetics, sporting goods, tires, electronics as well as
many other everyday items, and are used in medicine for purposes of
diagnosis, imaging and drug delivery.

Cover
(Basic Concepts of Crystal Structures)
BASIC CONCEPTS
OF
CRYSTAL
STRUCTURES

Basic Concepts Of Crystal Structures
1.1 Fundamental Concepts
Atoms self-organize in cryst als, most of the time. The crystalline
lattice, is a periodic array of the atoms. When the solid is not crystalline, it is
called amorphous. Examples of crystalline solids are metals, diamond and
other precious stones, ice, graphite. Examples of amorphous solids are
glass, amorphous carbon (a-C), amorphous Si, most plastics
To discuss crystalline structures it is useful to consider atoms as being
hard spheres, with well-defined radii. In this scheme, the shortest distance
between two like atoms is one diameter.
 Crystalline – periodic arrangement of atoms: definite repetitive pattern.
 Non-crystalline or Amorphous – random arrangement of at oms.

1.2 Unit Cells
The unit cell is the smallest structure that repeats itself by translation
through the crystal. We construct these symmetrical units with the hard
spheres. The most common types of unit cells are the faced-centered
cubic (FCC), the body-centered cubic (BCC) and the hexagonal close-
packed (HCP). Other types exist, particularly among minerals. The simple
cube (SC) is often used for didactical purpose, no material has this
structure.
SC (Simple Cubic): This arrangement is called simple cubic structure, and
the unit cell is called the simple cubic unit cell or primitive cubic unit cell.

Coordination number of a Simple Cube.
FCC (face centered cubic): Atoms are arranged at the corners and
center of each cube face of the cell.
BCC (Body Centered Cubic): Atoms are arranged at the corners of the
cube with another atom at the cube center.
HCP (Hexagonal close-packed): Cell of an HCP lattice is visualized as a
top and bottom plane of 7 atoms, forming a regular hexagon around a
central atom. In
between these

planes is a half hexagon of 3 atoms. There are two lattice parameters in
HCP, a and c, representing the basal and height parameters respectively
1.3 Metallic Crystal Structures
 Important properties of the unit cells
are
 The type of atoms and their radii R.
 Cell dimensions (side a in cubic cells,
side of base a and height c in HCP) in
terms of R.
 Number of atoms (n) per unit cell. For
an atom that is shared
with m adjacent unit cells, we only
count a fraction of the atom, 1/m.
 The coordination number (CN), which is the number of closest
neighbors to which an atom is bonded.
 The atomic packing factor (APF), which is the fraction of the volume of
the cell actually occupied by the hard spheres. APF = Sum of atomic
volumes/Volume of cell.
Unit
Cell
n CN a/R APF
SC 1 6 2 0.52
BCC 2 8 3 0.68
FCC 4 12 2 0.74
HCP 6 12 0.74

 Atomic packing factor (APF) or packing efficiency indicates how
closely atoms are packed in a unit cell and is given by the ratio of
volume of atoms in the unit cell and volume of the unit cell. APF=
Volume of atoms/Volume of unit cell

1.4. Density Computation
Density is the mass of an object divided by its volume. Density often has
units of grams per cubic centimeter (g/cm3). Remember, grams is a mass
and cubic centimeters is a volume (the same volume as 1 milliliter). It is
often used in identifying rocks and minerals. The density of a solid is that of
the unit cell. The formula for the density is
Where: n= number of atoms/unit cell
A= atomic weight
Vc=volume of unit cell (a3 for cubic)
NA = Avogadro's number (6.022 x 1023 atom/mol)

1.5. Polymorphism and Allotropy
 Polymorphism. This means 'many forms' and can be exhibited in a variety
of ways. Existence of substance into more than one crystalline forms.
Under different conditions of temperature and pressure, a substance
can form more than one type of crystals.
Examples: Mercuric
iodide (HgI) forms two
types of crystals
 Allotropy. Existence of an
element into more than
one physical forms and it
refers to an element. An
example of allotropy is carbon, which can exist as diamond, graphite,
and amorphous carbon.
 Allotropism is the
property of some
chemical elements to
exist in two or more
different forms, known
as allotropes of these
elements. Allotropes
are different structural
modifications of an
element; the atoms of
the element are

bonded together in a different manner. For example, allotropes of a
carbon include diamond and graphite.
1.6. Close-Packed Crystal Structure
The Face Centered Cubic (FCC) and Hexagonal Close Packed (HCP) are
related, since both structures are composed of stacked hexagonal layers.
They are built by packing spheres on top of each other. The FCC structure
can be constructed from the A - B - C - A - B - C . . . . . sequence. An
alternate sequence might be B - A - C - B - A - C ... The hexagonal close
packed structure can be made by piling layers in the A - B - A - B - A - B . . .
. . sequence. An alternative would be A - C - A - C - A . . . sequence.
1.7. Single Crystals
 A single crystal is a material in which the crystal lattice of the entire
sample is continuous and unbroken to the edges of the sample, with
no grain boundaries. The absence of the defects associated with grain
boundaries can give single crystals unique properties, particularly
mechanical, optical and electrical. These properties, in addition to
making them precious in some gems, are industrially used in
technological applications, especially in optics and electronics.
 Single crystal, any solid object in which an orderly three-dimensional
arrangement of the atoms, ions, or molecules is repeated throughout
the entire volume. Certain minerals, such as quartz and the gemstones,
often occur as single crystals; synthetic single crystals, especially silicon
and gallium arsenide, are used in solid-state electronic devices such
as integrated circuits and light-emitting diodes (LEDs).
 In the preparation of synthetic single crystals, special techniques are
employed to control the deposition of material upon one nucleus,

which often is a small single crystal of the substance obtained from a
previous preparation.
1.8. Polycrystalline Materials
 Polycrystalline or multicrystalline materials, or polycrystals are solids that
are composed of many crystallites of varying size and orientation.
Crystallites are also referred to as grains. They are small or even
microscopic crystals and form during the cooling of many materials.
 Polycrystalline materials have a microstructure composed of single
crystals and grain boundaries (GB). The thermal and mechanical
behavior of polycrystalline materials depends strongly on their
microstructure, where the texture (sizes and orientations) of single
crystals and the total area of GBs play a critical role. One example is
the well-known Hall–Petch relationship, which shows that the strength
of the polycrystals increases as the average size of the single crystal is
reduced. Moreover, the microstructures depend on the processing
techniques (for example, rate of cooling or extent of deformation) and
lead to different macroscopic behavior.
 The orientation of the crystals (we call them grains ) are different from
each other.

 The boundaries which join them are known as grain boundaries: It is
which the orientation of the crystal changes.
 The point at which three boundaries meet is called the triple junction.
1.9. Anisotropy
 Anisotropy is the property of substances to exhibit variations in physical
properties along different molecular axes. It is seen in crystals, liquid
crystals and, less commonly, in liquids.
 For example, consider the primitive cubic crystal lattice structure shown
below. In this instance, all of the atoms are of the same element.

 To recognize this structure's anisotropy, consider the distances A-B, A-C
and A-D; they are all different.
 Assuming that A-B distance is 1 unit, A-C is √2 units, and A-D is √3 units.
 Viewing the structure along an axis following the direction A-B looks
different from along an axis following the directions A-C or A-D. This
leads to different physical and mechanical properties in a single crystal
along the different axes.
Additional Information:
 Anisotropy is most easily observed in single crystals of solid elements
or compounds, in which atoms, ions, or molecules are arranged in
regular lattices. In contrast, the random distribution of particles in
liquids, and especially in gases, causes them rarely, if ever, to be
anisotropic.
 A familiar example of anisotropy is the difference in the speed of
light along different axes of crystals of the mineral calcite. Another
example is the electrical resistivity of selenium, which is high in one
direction but low in the other; when an alternating current is applied to
this material, it is transmitted in only one direction (rectified), thus
becoming a direct current.
1.10. Amorphous (Non-crystalline Solids) Materials
 These are solids with irregular geometrical shape due to random
distribution of particles in three dimensions.
 These are made up of randomly orientated atoms, ions, or molecules
that do not form defined patterns or lattice structures.

 Some common examples of non crystalline solids are coke, glass,
plastic, and rubber. The solid materials can be composed of ions,
molecules or metal ions which are held together with strong attractive
forces between them. The position of constituent particles of solids is
essentially fixed in space therefore they cannot change their position.
Formation of Atoms in Different Types of Solids
Difference Between Crystalline and Non-Crystalline Materials
Crystalline
• Crystalline solids have sharp and well defined melting points.
• Crystalline solids have an extended 3-D arrangement of constituent
particles in which particles are generally locked into their positions.
• Crystals have well-defined edges and faces which can diffract x-rays
and have sharp melting points.
• Crystalline solids have long range ordered arrangement of particles.
They can cleaved along definite planes and are anisotropic in nature
in which properties depends on the direction of arrangement of
particles.
Non-Crystalline
• Non-crystalline solids tend to soften slowly over a wide temperature
range and have a range of melting point not the sharpen melting
points.

• Non crystalline solids have irregular, curved surfaces which do not give
x-ray diffraction patterns.
• Non crystalline solids have short range order arrangement of particles
and can easily soften in a range of temperature. They undergo
irregular breakage and isotropic in nature in which properties do not
depend on the direction of arrangement of particles.

Metals
Characterized by metallic inter atomic bonding with valence shell
electrons forming a cloud of electrons around the atoms or ions. Are solid
chemical elements except hydrogen. Opaque, lustrous Elements that are
good conductors of Heat and Electricity. Most of it are malleable and
ductile. In general, metals are denser than the other elemental substances.
―Metals are a unique class of toxicants since they cannot be broken down to
on-toxic forms.‖
Metals are used in…
• Transportation;
• Aerospace;
• Computers and other devices that requires conductors;
• Construction;
• Biomedical Applications;
• Electrical power production and distribution;
• Farming and household conveniences.
TYPES OF METALS
1. Ferrous Metals
2. Non-Ferrous Metals
Ferrous Metals: Non-Ferrous Metals:
- Cast Iron - Stainless Steel - Aluminum - Beryllium
- Carbon Steel - Tool Steel - Copper - Magnesium
- Alloy Steel - HSLA Steel - Nickel - Tin
- - - Titanium - Zinc

Ferrous Metals:
Cast Iron
Defined as an iron alloy with more than 2% carbon as the main alloying
element. In addition to carbon, cast irons must also contain from 1% to 3%
silicon which combined with carbon. Has a much lower melting temperature
than steel and is more fluid and less reactive with molding materials.
However, they do not have enough ductility to be rolled or forged.
TYPES OF CAST IRON
• White Iron
• Gray Iron
• Ductile Iron
• Malleable Iron
White Cast Iron - Characterized by the prevalence of carbides, impacting,
high compressive strength; Hardness; Good resistance to wear
Gray Iron - Characterized with graphite in the microstructure, giving good
machinability and good resistance to wear and galling.
Ductile Iron- Gray iron with small amounts of magnesium and cesium which
modulates the graphite, resulting high strength and high ductility.
Malleable Iron - White cast iron heat-treated to improve higher ductility.
Carbon Steel
Is a malleable, iron-based metal containing less than 2 % carbon, small
amounts of manganese and other trace elements. Specified by chemical
composition, mechanical properties, method of deoxidation, or thermal
treatment.
Alloy Steel
Steels that contain specified amounts of alloying elements – other than
carbon and the commonly accepted amounts of manganese, copper,
silicon, sulfur, and phosphorus. Added to change mechanical or physical
properties. A steel is considered to be an alloy when the maximum of the

range given for the content of alloying elements exceeds one or more of
these limits: 1.65% Mn, 0.60% Si, or 0.60% Cu.
Stainless Steel
Generic name for a number of different steels used primarily for their
resistance to corrosion.
Commonly divided into Five Groups
1. Martensitic
2. Ferritic
3. Austenitic
4. Duplex
5. Precipitation-Hardening

Tool Steel
Defining properties include resistance to wear, stability during heat
treatment, strength at high temperature and toughness. Always heat treated.
Classified into several broad groups, some of which are further divided into
subgroups according to alloy composition, hardenability, or mechanical
similarities.
HSLA Steel
High-Strength Low Alloy have higher strength to weight ratio than
conventional low carbon steels. They can be used in thinner sections. Usually
low carbon steels with up to 1.5% manganese, strengthened by small
additions of elements, such as columbium, copper, vanadium or titanium.
Non- Ferrous Metals:
Aluminum - Silvery white metal with many desirable characteristics. It is light,
nontoxic, nonmagnetic and non-sparking. Easily formed, machined, and
cast. Also, soft and lacks strength but very useful properties. Abundant
element in the earth‘s crust, but is not found free in nature. Aluminum‘s
mechanical and physical properties, is an extremely convenient and widely
used metal.
Beryllium - Highest melting points of the light metals. It has excellent thermal
conductivity, is nonmagnetic and resists attack by concentrated nitric acid.
A very light weight metal with a high modulus of elasticity High specific heat
and high specific strength. Commonly use as: alloying agents in the
production of beryllium-copper, used in x-rays.
Copper - Provides diverse range of properties: good thermal and electrical
conductivity, corrosion resistance, ease of forming, ease of joining and color.
Relatively low strength to weight ratios and low strengths at elevated
temperatures. Has a disagreeable taste and peculiar smell. Commonly use
as: tube shapes, forgings, wires, castings, rod and plate.

Magnesium - Lightest structural metal. Has a high strength to weight ratio. Is
sensitive to stress concentration, however, notches sharp corners, and abrupt
section changes should be avoided. Easiest of the structural metals to
machine and they can be shaped and fabricated. Commonly use as:
metalworking processes and welding.
Nickel - Fits many applications that require specific corrosion resistance or
elevated temperature strength. Some are among the toughest structural
materials known. Have ultrahigh strength, high proportional limits, and high
moduli of elasticity. Commercially pure nickel has good electrical, magnetic,
and magneto strictive properties.
Tin - Characterized by a low melting point. The metal is nontoxic, solderable,
and has high boiling point. Also used in bronze, pewter and bearing alloys.
Principal uses for tin are a constituent of solder and as coating for steel.
Titanium - There are three structural types of titanium alloys:
1. Alpha Alloys – non heat treatable and are generally very weld-able; low to
medium strength, good notch toughness, reasonably good ductility.
2. Alpha-Beta Alloys – are heat treatable and most are weldable. Strength
levels medium to high.
3. Beta or near-beta Alloys – are readily heat treatable, generally weldable,
capable of high strengths and good creep resistance to intermediate
temperatures; have good combinations of properties in sheet , heavy
sections, fasteners and spring applications.
Iron - Relatively low melting point and boiling point. Zinc are after alloying
with small amounts of other metals or as a protective coating for steel. Is also
used to make brass, bronze, coil and activators and stabilizers for plastics.

Polymers
The word polymer is derived from the classical Greek words poly
meaning ―many‖ and meres meaning ―parts‖. A polymer is a molecular
compound where molecules are bonded together in long repeating
chains of identical structures which are known as monomers. These
materials, polymers, have unique properties and can be tailored
depending on their intended purpose.
Figure no.1 Monomers and Polymers
The materials have unique properties, depending on the type of
molecules being bonded and how they are bonded. Some polymers
bend and stretch, like rubber and polyester. Others are hard and tough,
like epoxies and glass. A common example of a polymer is the polythene
which consists of large number of ethane molecules.
Figure no. 2 Polythene

I. Polymerization
The process by which relatively small molecules (monomers) combined
chemically to produce a very large chainlike/network molecule (polymer)
is called polymerization. The monomer molecules may be all alike, or they
may represent two, three, or more different compounds. Usually at least
100 monomer molecules must be combined to make a product that has
certain unique physical properties—such as elasticity, high tensile strength,
or the ability to form fibers—that differentiate polymers from substances
composed of smaller and simpler molecules; often, many thousands of
monomer units are incorporated in a single molecule of a polymer. The
formation of stable covalent chemical bonds between the monomers sets
polymerization apart from other processes, such as crystallization, in which
large numbers of molecules aggregate under the influence of weak
intermolecular forces.
Figure no. 3 Polymerization Process
II. Types of Polymers
According to Ali (2017), polymers have 2 different types namely:
 Naturally Occurring Polymer – it is the polymers that occur in
nature and can be extracted. This is also the result of the
molecular polymer chain created by Mother Nature. Common
examples of naturally occurring polymers are proteins and
starches.

Figure no. 4 Starches and protein
 Synthetic Polymers – this polymer derived from petroleum oil, and
made by scientists and engineers. To be simpler, synthetic
polymers are those which are human-made polymers. Synthetic
polymers are sometimes referred as ―plastics‖, of which the well-
known ones are nylon and polyethylene.
Figure no. 5 Nylon and polyethylene
III. Classification of Polymers
A. Chemical Structure.
On the basis of chemical structure, polymers are classified as:
 Homopolymer – is a polymer which derived from one species of
monomer.

Figure no. 6 Homopolymers
 Copolymer – is a polymer which derived from two or more
different types of monomers.
Figure no. 7 Copolymers
Moreover, copolymer has three different types and these are
random copolymer, alternating copolymer and block copolymer.
Figure no. 8 Types of copolymer

B. Polymeric Structure
On the basis of polymeric structure, polymers are classified as:
 Linear Polymer - are those polymers in which the repeat units are
joined together end to end in single chains.
Figure no. 9 Linear structure
 Branched Polymer - polymers which have side-branch chains
that are connected to the main ones are called branched
polymers.
Figure no. 10 Branched structure
 Crosslinked Polymer - adjacent linear chains are joined one to
another at various positions by covalent bonds.

Figure no. 11 Crosslinked Structure
C. Tacticity
Tacticity is the relative spatial arrangement of atoms or
molecules within a macromolecule. With the change in tacticity,
properties of the material change such as amorphous and
crystalline behaviour, tg, tm are affected. In tacticity, polymers are
classified as:
 Isotactic Polymers – polymers where the side groups are
attached on one side of the backbone chain.
 Syndiotactic Polymers – polymers where the side groups are
arranged alternatively on the backbone chains.
 Atactic Polymers – polymers where the side groups or pendant
groups are attached randomly along the backbone chain.
Figure No. 12 Three classification of tacticity
D. Thermal Behavior
Thermal behavior refers to the behavior of polymers upon
heating. Polymers are classified as:
 Thermoplastic - soften when heated and harden when cooled.
This is totally reversible and repeatable. Most linear polymers and
branched structure polymers with flexible chains are
thermoplastics.

Figure No. 13 Thermoplastic molecular structure
Figure No. 14 Thermoplastic‘s Examples
 Thermosets – do not soften when heated due to strong covalent
crosslinks. Thermoset polymers are generally harder and stronger
than thermoplastics and have better dimensional stability.

Figure No. 15 Thermosets molecular structure
Figure No. 16 Thermosets Examples
E. Molecular Forces
Polymers can also be classified on the basis of molecular forces
into two types.
 Elastomers – are the polymers that can be stretched like elastics
and also will come back to their original shape on releasing the
force. Very common example of elastomers is natural rubber.

Figure No. 17 Natural rubber
 Fibers – are solids having thread like structure possessing strong
intermolecular force. Due to this strong force of attraction, they
have high tensile strength. For example: Nylon 66, Dacron, etc.
Figure No. 18 Nylon and Dacron
F. Methods of Synthesis
Polymers can also be classified on the basis of methods of
synthesis into two different types.
 Addition polymers – A polymer formed by direct addition of
repeated monomers without the elimination of any molecule is
called addition polymer. The addition polymers are generally
prepared from unsaturated compounds. For example, natural
rubber is obtained as latex from rubber trees. The monomer of
natural rubber is isoprene. There may be as many as 11000 to
20000 isoprene units in a polymer chain of natural rubber.

Figure No. 19 Latex
 Condensation polymers – These polymers are formed by the
condensation of two or more monomers with the elimination of
simple molecules like water and alcohol. Following are the
examples of two important condensation polymers:
1. Nylon - Nylon fiber is produced by pushing molten nylon
through tiny openings in a device called a spinneret; the
nylon pieces then harden into a filament after they are
exposed to air. Nylon possesses many properties that make it
a very useful fiber in many applications. It is very strong and
elastic; it‘s also easy to wash, and can usually be washed with
similar items and does not typically require specialty
laundering arrangements. Nylon dries rather quickly and t
retains its shape rather well after laundering, which ensures
longevity of the garment. Nylon fiber is very responsive and
resilient as well as relatively resistant to heat, UV rays and
chemicals. One of the most common uses for nylon is in
women's stockings or hosiery. It is also used as a material in
dress socks, swimwear, shorts, track pants, active wear,
windbreakers, draperies and bedspreads.

Figure No. 20 Nylon Synthesis
2. Polyester - Polyester is often used in outerwear because of its
high tenacity and durability. It is a strong fiber and
consequently can withstand strong and repetitive
movements. Its hydrophobic property makes it ideal for
garments and jackets that are to be used in wet or damp
environments--coating the fabric with a water-resistant finish
intensify this effect.
Figure No. 21 Polyester Synthesis
IV. Classification of Plastics
One very common example of polymers is plastics. Plastic is a
synthetic material made from a wide range of organic polymers
such as polyethylene, PVC, nylon, etc., that can be molded into
shape while soft and then set into a rigid or slightly elastic form.
Plastics are usually classified by their chemical structure of the
polymer's backbone and side chains. Plastics can also be classified

by the chemical process used in their synthesis, such as
condensation, polyaddition, and cross-linking.
The Society of the Plastics Industry (SPI) established a
classification system in 1988 to allow consumers and recyclers to
identify different types of plastic. Manufacturers place an SPI code,
or number, on each plastic product, usually moulded into the
bottom. This guide provides a basic outline of the different plastic
types associated with each code number.
1. Polyethylene Terephthalate (PET or PETE) - a strong, stiff
synthetic fiber and resin, and a member of the polyester
family of polymers. PET is produced by the polymerization of
ethylene glycol and terephthalic acid. Ethylene glycol is a
colourless liquid obtained from ethylene, and terephthalic
acid is a crystalline solid obtained from xylene. PET is the most
widely recycled plastic. PET bottles and containers are
commonly melted down and spun into fibres for fibrefill or
carpets.
Figure No. 22 Structure of Polyethylene Terephthalate
Figure No. 23 Polyethylene Terephthalate Examples

2. High-Density Polyethylene (HDPE) - HDPE is a hydrocarbon
polymer prepared from ethylene/petroleum by a catalytic
process. It is a kind of thermoplastic which is famous for its
tensile strength. Its unique properties can stand high
temperatures. HDPE products are commonly recycled. Items
made from this plastic include containers for milk, motor oil,
shampoos and conditioners, soap bottles, detergents, and
bleaches. It is NEVER safe to reuse an HDPE bottle as a food or
drink container if it didn‘t originally contain food or drink.
Figure No. 24 Structure of High-Density Polyethylene
Figure No. 25 High-Density Polyethylene Examples
3. Polyvinyl Chloride (PVC) - Polyvinyl Chloride is sometimes
recycled. PVC is used for all kinds of pipes and tiles, but is most
commonly found in plumbing pipes. This kind of plastic should
not come in contact with food items as it can be harmful if
ingested.

Figure No. 25 Structure of Polyvinyl Chloride
Figure No. 26 Polyvinyl Chloride Example
4. Low-Density Polyethylene (LDPE) - Low-Density Polyethylene is
sometimes recycled. It is a very healthy plastic that tends to
be both durable and flexible. Items such as cling-film,
sandwich bags, squeezable bottles, and plastic grocery bags
are made from LDPE.
Figure No. 27 Low-Density Polyethylene Structural Formula

Figure No. 28 Low-Density Polyethylene Example
5. Polypropylene (PP) - Polypropylene is occasionally recycled.
PP is strong and can usually withstand higher temperatures. It
is used to make lunch boxes, margarine containers, yogurt
pots, syrup bottles, prescription bottles. Plastic bottle caps are
often made from PP.
Figure No. 29 Polypropylene Structural Formula
Figure No. 30 Polypropylene Example
6. Polystyrene - Polystyrene is commonly recycled, but is difficult
to do. Items such as disposable coffee cups, plastic food
boxes, plastic cutlery and packing foam are made from PS.

Figure No. 30 6. Polystyrene structural formula
Figure No. 30 Polystyrene Example
7. Other – also called as polycarbonate or miscellaneous
plastics, a hard plastic that appears to be almost as sturdy as
glass, is known to contain Bisphenol A (BPA). BPA is a
chemical that mimics estrogen and causes many health and
developmental problems.
Figure No. 30 Miscellaneous Plastics Examples

Devices
(Engineered Nano Materials)
Engineered
Nano
Materials

INTRODUCTION
The rapid development of engineered nanomaterials (ENMs) has
grown dramatically in the last decade, with increased use in consumer
products, industrial materials, and nanomedicines. Engineered nanomaterials
are found in many products we use every day. Because of their size, they
have interesting properties in many applications. For example, they are used
in electrical appliances, medicines, cleaning products, cosmetics (such as a
component of some sunscreens), paints and building materials, textiles (for
example mainly to get an antibacterial effect), pollution control applications.
Globally, the ENMs are now becoming a significant fraction of the
material flows in the economy. We are already reaping the benefits of
improved energy efficiency, material use reduction, and better performance
in many existing and new applications that have been enabled by these
technological advances (Keller et. al., 2013).
In the Asia-Pacific Region like Thailand, China, India, Korea, Japan,
Australia, and many other countries, the commercialization of products
containing engineered nanomaterials have widely increased (Azoulay et. al.,
2013). The use of engineered nanomaterials has been a huge contribution in
our daily lives.
Though ENMs have been invented and developed still, many do not
know and are unfamiliar the about this nanomaterials and nanoparticles.
Knowing these terms as well as their deeper meaning and functions can
improve our knowledge in science and technology and might push us to
discover new things. To widen our knowledge about such topic, the
Engineered Nanomaterials, Two Main Sources of Nanomaterials, Properties of
Nanomaterials, Examples of Engineered Nanomaterials and the Application
of Engineered Nanomaterials are discussed on the next pages.
ENGINEERED NANOMATERIALS
Engineered nanomaterials are intentionally produced and designed with
physico-chemical properties for specific purpose or function. They are
produced by scientist, or any experts. They also have unique properties that
make them useful and dangerous.
Structure of Nanomaterials
The structure of the nanomaterials can be classified by their dimensions:
the zero-dimensional and one-dimensional nanostructures.
The zero-dimensional nanostructures are nanoparticles. Nanopart icles
have one dimension that measures 100 nanometers or less. The properties of

many conventional materials change when formed from nanoparticles. They
are used, or being evaluated for use, in many fields. The list below introduces
several of the uses under development.
The one-dimensional nanostructures are whiskers, fibers (or fibrils),
nanowires and nanorods. In many cases, nanocables and nanotubes are
also considered one-dimensional structures. Thin films are considered as two-
dimensional nanostructures. Colloids bearing complex shapes have three-
dimensional nanostructures.
Whiskers. One-dimensional (1D) cuprite (Cu2O) nano-whiskers with
diameter of 15–30 nm are obtained from liquid deposition method at 25 °C
by adding a surfactant, cetyl trimethyl ammonium bromide (CTAB), as a
template. TEM and HRTEM show that the nano-whiskers exhibit a well-
crystallized 1D structure of more than 200 nm in length, and confirms that the
nano-whiskers grow mainly along the 〈111〉 direction.
Fibers. Fibers having an effective gradient index profile with designed
refractive index distribution can be developed with internal nanostructuring
of the core composed of two glasses. As proof-of-concept, fibers made of
two soft glasses with a parabolic gradient index profile are developed.
Energy-dispersive X-ray spectroscopy reveals a possibility of selective diffusion
of individual chemical ingredients among the sub-wavelength components
of the nanostructure.
Nanowires. Nanonowires are structures that have a thickness or diameter
constrained to tens of nanometers or less and an unconstrained length. At
these scales, quantum mechanical effects are important—which coined the
term "quantum wires". Nanowire offers a coaxial gate-dielectric-channel
geometry that is ideal for further downscaling and electrostatic control, as
well as heterostructure-based devices on Si wafers.
Nanorods. One-dimensional MoO2–Co2Mo3O8@C nanorods were
synthesized by using MoO3@ZIF-67 composites as a precursor for the first time,
and it is found that the Co2Mo3O8 species and its composite have excellent
OER activities. The MoO2–Co2Mo3O8@C nanorods present favorable
electrocatalytic advantages toward OER in alkaline solution, requiring an
overpotential of only 320 mV to deliver a current density of 10 mA cm−2.
Nanocables. Cables made of carbon nanotubes are inching toward
electrical conductivities seen in metal wires, and that may light up interest
among a range of industries. Highly conductive nanotube-based cables
could be just as efficient as traditional metals at a sixth of the weight.
Nanot ubes. A nanotube is a hollow nanowire, typically with a wall
thickness on the order of molecular dimensionsThe smallest (and most
interesting) nanotube is the single-walled carbon nanotube (SWNT) consisting

of a single graphenesheet rolled up into a tube. SWNTs are ideal systems for
investigating fundamental properties in one-dimensional electronic systems
and have the potential to revolutionize many aspects of nano/molecular
electronics.
Four Types of Engineered Nano materials
There are four types of engineered nanomaterials, namely: Carbon
Based, Metal Based, Dendrimers and Composites.
Figure 1. Types of Nanomat erials
I. CARBON BASED- These nanomaterial are composed mostly of carbon,
most commonly taking the form of a hollow spheres, ellipsoids, or tubes.
Spherical and ellipsoidal carbon nanomaterials are referred to as
FULLERENES, while cylindrical ones are called nanotubes (Carbon
Nanotubes) CNTs.

Figure 2. Carbon Based Nanomat erials in Sample Preparat ion
II. METAL BASED -These nanomaterials include quantum dots, nanogold
(also called gold nanoparticles, are small particles that are generally
found as a colloidal solution, and its color ranges from clear blue to
red), nanosilver, and metal oxides, such as titanium dioxide.
III. DENDRIMERS – These nanomaterials are nano-sized polymers built from
branched units. The surface of the dendrimer has numerous chain
ends, which can be tailored to perform specific chemical functions.
This property could also be useful for catalysis. Also, because three-
dimensional dendrimers contain interior cavities into which other
molecules could be placed, they may be useful for drug delivery.
Figure 3. Dendrimers
IV. COMPOSITES- Composites combine nanoparticles or with other nano
particles or with larger, bulk-type materials. The composites may be
any combination of metal based carbon based or polymer based
nanomaterials with any form of metal, ceramic or polymer bulk
materials.
Met al Based - a composite material with at least two constituent
parts, one being a metal necessarily, the other
material may be a different metal or another
material.
Carbon Based - carbon composite materials is carbon fiber or
fabric as reinforcement by chemical vapor
infiltration of pyrolytic carbon or liquid impregnation
- carbonization of resin carbon, carbon is a pure
bitumen matrix composition carbon multi-phase
structure.
Polymer Based - provide large amount of flexibility and

lightweight to a final product.
Figure 4. Composit es
TWO MAIN SOURCES OF NANOMATERIALS
There are two main sources of nanomaterials the Natural Sources and
Anthropogenic Sources.
I. Natural Sources
Natural sources include but are not limited to volcanoes, viruses, ocean
spray, dust storms, bacteria, and bush fires. Additionally, the human body
uses natural nanoscale materials such as proteins and other molecules, to
control the body's many systems and processes (Kumar et. al., 2014).
Figure 5. Examples of Nat ural Sources
II. Anthropogenic Sources
Anthropogenic nanoparticles are man-made and may result in
incidental exposure. The anthropogenic nanoparticles, also known as
engineered nanoparticles (ENPs), exhibit specific size ranging from 1–100 nm.
They are pure materials with controlled surfaces. There are two types of
anthropogenic sources, the unintentionally produced and intentionally
produced.

Unint ent ionally Produced
Combustion aerosols, particularly motor vehicle exhaust emission, coal
fly ash, and wielding operations (Kumar et. al., 2014).
Int ent ionally Produce
Nanowires, nanotubes, quantum dots, and fullerenes, mostly
composed of metals and metal oxides (Kumar et. al., 2014).
Figure 6. Examples of Ant hropogenic Sources
EXAMPLES OF ENGINEERED NANOMATERIALS
Engineered nanoparticles may be bought from commercial vendors or
generated via experimental procedures by lab researchers. Some examples
of engineered nanomaterials are: fullerenes or carbon buckeyballs; carbon
nanotubes; metal or metal oxide nanoparticles;
and quantum dots.
I. Fullerenes or Carbon Buckeyballs
Fullerenes composed of less than 300
carbon atoms, or endohedral fullerenes, are
commonly known as ―buckyballs‖, and include
the most common fullerene,
buckminsterfullerene, C60. If the C60 molecule
were the size of a soccer ball, then the soccer
ball in turn would be about the size of the earth.
Giant fullerenes, or fullerenes with more than
300 carbon atoms, include single-shelled or multi-shelled carbon structures,
onions, and nanotubes. The chemistry of fullerenes is rich and varied and
allows the properties of basic fullerenes to be tailored to a given application
(Yadav & Kumar, 2008).

Figure 8. Fullerene act ing as N-Type in solar cell
Currently, the record efficiency for a bulk heterojunction polymer solar
cell is a fullerene/polymer blend. The fullerene acts as the n-type
semiconductor (electron acceptor). The n-type is used in conjunction with a
p-type polymer (electron donor), typically a polythiophene. They are
blended and cast as the active layer to create what is known as a bulk
heterojunction.
II. Carbon Nanotubes
Since the discovery in 1991 by the Japanese scientist ―Sumio Iijima‖,
carbon nanotubes have been of great interest, both from a fundamental
point of view and for future applications. Different types of carbon nanotubes
can be produced in various ways (Aqel et. al., 2012).
It was named ―carbon nanotubes‖ since they have a tubular structure
of carbon atom sheets, with a thickness scaled in less than a few nanometers.
A carbon nanotube is a simple system composed of a reasonable number of
atoms, which enable us to calculate theoretical electronic structures in detail
through computer simulations. As a result, single-wall carbon nanotubes were
found to be electrically semiconducting or metallic depending upon their
diameters and chirality. Such important physical properties were later proved
experimentally in various electrical and optical measurements.
One of the industrial applications utilizing the
unique properties of carbon nanotubes is a transistor.
This and other possible applications of carbon
nanotubes play an important role in
nanotechnology, and are currently being
investigated the world over.
Figure 9. Transist or

Table 1. Example and Applicat ion of Carbon Nanot ube
III. Metal or Metal Oxide Nanoparticles
Metal or Metal oxides play a very important role in many areas of
chemistry, physics and materials science. The metal elements are able to
form a large diversity of oxide compounds. These can adopt a vast number
of structural geometries with an electronic structure that can exhibit metallic,
semiconductor or insulator
character. In technological
applications, oxides are
used in the fabrication of
microelectronic circuits,
sensors, piezoelectric
devices, fuel cells, coatings
for the passivation of
surfaces against corrosion,
and as catalysts (Fernandez-
Garcia & Rodriguez, 2007).
Currently, several types of metal oxides nanoparticles play a very
important role in numerous areas of Physics, Chemistry and in Materials
science.
Table 2. Examples and Applicat ions of Met al Oxide Nanopart icles
Example of Carbon
Nanotube
Application
 Transistor Transistor is a
semiconductor
device that can
conduct and insulate.
It converts audio
waves into electronic
waves and resistor,
controlling electronic
current.
Example of Metal Oxide
Nanoparticles
Applications
 CuO NPs The CuO nanoparticles are used
in microwave irradiation process,
also as redox catalyst as well as
catalyst in several oxidation
process. They are also used in
photoconductive and
photothermal applications.
 ZnO NPs ZnO nanoparticles are used as
UV blockers in sun locations,
mixed varsitors, solar cell and
optoelectronics, in gas sensors
and also in catalysts for various
types of organic reactions .

Figure 10. CuO NPs in Microwave (left); ZnO NPs in cosmetics such as Sun
Screen (right)
IV. Quantum Dots
Quantum dots were
discovered by the Russian Physicist
Alexey I. Ekimov in 1981. These tiny
nanoparticles have diameters which range
from 2 nanometers to 10 nanometers, with
their electronic characteristics
depending on their size and shape. The
particles differ in color depending on their
size, the image on the right shows glass
tubes with quantum dots of
perovskite nanocrystals with differing colors
due to varying synthesis reaction times.
This results in different nanocrystal size
(Chilton, 2014).

Table 3. Examples and Applicat ions of Quant um Dot s
APPLICATION OF ENGINEERED NANOMATERIALS
I. Fuel cells
A fuel cell is an electrochemical energy conversion device that converts
the chemical energy from fuel (on the anode side) and oxidant (on the
cathode side) directly into electricity. The heart of fuel cell is the electrodes.
The performance of a fuel cell electrode can be optimized in two ways; by
improving the physical structure and by using more active electro catalyst.
A good structure of electrode must provide ample surface area, provide
maximum contact of catalyst, reactant gas and electrolyte, facilitate gas
transport and provide good electronic conductance. In this fashion the
structure should be able to minimize losses.
II. Carbon nanotubes - Microbial fuel cell
Microbial fuel cell is a device in which bacteria consume water-soluble
waste such as sugar, starch and alcohols and produces electricity plus clean
water. This technology will make it possible to generate electricity while
treating domestic or industrial wastewater. Microbial fuel cell can turn
different carbohydrates and complex substrates present in wastewaters into
a source of electricity
Example of Quantum Dots Definition / Applications
 Quantum Dot Light
Emitting Diodes (QD-
LED
Quantum dot light emitting diodes
(QD-LED) and ‗QD-W.hite LED‘ are
very useful when producing the
displays for electronic devices
because they emit light in highly
specific Gaussian distributions. QD-
LED displays can render colors very
accurately and use much less
power than traditional displays.
 Biological Applications The latest generation of quantum
dots has great potential for use in
biological analysis applications. They
are widely used to study intracellular
processes, tumor targeting, in vivo
observation of cell trafficking,
diagnostics and cellular imaging at
high resolutions.

III. Catalysis
Higher surface area available with the nanomaterial counterparts, nano-
catalysts tend to have exceptional surface activity. For example, reaction
rate at nano-aluminum can go so high, that it is utilized as a solid-fuel in
rocket propulsion, whereas the bulk aluminum is widely used in utensils.
Nano-aluminum becomes highly reactive and supplies the required thrust
to send off pay loads in space. Similarly, catalysts assisting or retarding the
reaction rates are dependent on the surface activity, and can very well be
utilized in manipulating the rate-controlling step.
IV. Phosphors for High-Definition TV
The resolution of a television, or a monitor, depends greatly on the size of
the pixel. These pixels are essentially made of materials called "phosphors,"
which glow when struck by a stream of electrons inside the cathode ray tube
(CRT).
The use of nanophosphors is envisioned to reduce the cost of these
displays so as to render high-definition televisions (HDTVs) and personal
computers affordable to be purchase.
V. Next-Generation Computer Chips
The microelectronics industry has been emphasizing miniaturization,
whereby the circuits, such as transistors, resistors, and capacitors, are
reduced in size. By achieving a significant reduction in their size, the
microprocessors, which contain these components, can run much faster,
thereby enabling computations at far greater speeds.
Nanomaterials help the industry break these barriers down by providing
the manufacturers with nanocrystalline starting materials, ultra-high purity
materials, materials with better thermal conductivity, and longer-lasting,
durable interconnections (connections between various components in the
microprocessors)
VI. Sun-screen Lotion
Prolonged UV exposure causes skin-burns and cancer. Sun-screen lotions
containing nano-TiO2 provide enhanced sun protection factor (SPF) while
eliminating stickiness. The added advantage of nano skin blocks (ZnO and
TiO2) arises as they protect the skin by sitting onto it rather than penetrating
into the skin (Alagarasi, 2016).

PROPERTIES OF NANOMATERIALS
There are four (4) properties of nanomaterials, namely: Optical Properties;
Electrical Properties; Mechanical Properties; and Magnetic properties.
I. Optical Properties
One of the most fascinating and useful aspects of nanomaterials is their
optical properties. Applications based on optical properties of nanomaterials
include optical detector, laser, sensor, imaging, phosphor, display, solar cell,
photocatalysis, photoelectrochemistry and biomedicine. The optical
properties of nanomaterials depend on parameters such as feature size,
shape, surface characteristics, and other variables including doping and
interaction with the surrounding environment or other nanostructures.
II. Electrical Properties
Electrical Properties of Nanoparticles‖ discuss about fundamentals of
electrical conductivity in nanotubes and nanorods, carbon nanotubes,
photoconductivity of nanorods, electrical conductivity of nanocomposites.
One interesting method which can be used to demonstrate the steps in
conductance is the mechanical thinning of a nanowire and measurement of
the electrical current at a constant applied voltage.
III. Mechanical Properties
Mechanical Properties of Nanoparticles‖ deals with bulk metallic and
ceramic materials, influence of porosity, influence of grain size,
superplasticity, filled polymer composites, particle-filled polymers, polymer-
based nanocomposites filled with platelets, carbon nanotube-based
composites.
The discussion of mechanical properties of nanomaterials is, in to some
extent, only of quite basic interest, the reason being that it is problematic to
produce macroscopic bodies with a high density and a grain size in the
range of less than 100 nm.
IV. Magnetic properties
Bulk gold and Pt are non-magnetic, but at the nano size they are
magnetic. Surface atoms are not only different to bulk atoms, but they can
also be modified by interaction with other chemical species, that is, by
capping the nanoparticles.
This phenomenon opens the possibility to modify the physical properties
of the nanoparticles by capping them with appropriate molecules. Actually,
it should be possible that non-ferromagnetic bulk materials exhibit
ferromagnetic-like behavior when prepared in nano range (Alagarasi, 2016).

PROCESSES FOR SYNTHESIS OF NANOPARTICLES
There are two processes for synthesis of nanoparticles, namely: Top-
down and Bottom-up Processes.
Table 4. Top-down and Bot t om-up Processes
HE
ALT
H
HA
ZA
RD
S
AN
D
RIS
K
CA
USE
D
BY
NA
NO
MA
TER
IAL
S
The engineered nanomaterials pose risks to workers and consumers,
and when they become airborne, they cause broader effects on the
environment and human health. Its increasing proportion in the atmosphere is
a potential threat. In this, the past studies are reviewed to identify the types,
effect-initiating properties, potential exposure pathways, and determine the
effects on humans and atmospheric environment (Gokhale, 2015).
Table 5. Possible Risks of Nanomat erials
Nanomaterials Possible Risks
Carbon nanomaterials, silica
nanoparticle
Pulmonary inflammation,
granulomas, and fibrosis
Carbon, silver and gold
nanomaterials
Distribution into other organs
including the central nervous
Top-down Process Bottom-up Process
- Involves the particle size
reduction to nano size.
- Involves the growth of
nanoparticles from atomic
size particles.
- The process is used only for
hard and brittle materials.
- The process is used for gas,
liquids and solids as well.
- All particles of the precursor
may not break down to the
required particle size.
- More control over particle
size.
- The noncrystalline materials
prepared by this process
maybe contaminated by
milling tools and
atmosphere.
- Less chances of
contaminations.
- Example: Ball Milling - Examples: Sol gel method
and Gas condensation
method

system
Quantum dots, carbon and TiO2
nanoparticles
Skin penetration
MnO2, TiO2, and carbon
nanoparticles
May enter brain through nasal
epithelium olfactory neurons
TiO2, Al2O3, carbon black, Co, and
Ni nanoparticles
May be more toxic than micron
sized particles
(Ray et. al., 2010)

Cover
(THE CHEMISTRYOF THE ENVIRONMENT)
CHEMISTY OF THE
ENVIRONMENT

The Chemistry of the Environment
ENVIRONMENT is the total of all surroundings of a living organism,
including natural forces and other living things. Which provide conditions for
development and growth as well as of danger and damage.
Environment that surrounds us. Different organisms live in different type
of surroundings such as air, water and soil. Different kinds of living organisms
share these surroundings with other. Chemistry of the environment deals with
the study of the origin, transport, reaction, effects and fates of chemical
species in the environment.
There are four components of environment
Biosphere- the regions of the surface, atmosphere, and hydrosphere of
the earth occupied by living organisms.
- supports the life such as
animals, human
Atmosphere- is a layer or a set of layers of gases surrounding a planet
or other material body, that is held in place by the gravity of that body.
Hydrosphere- is the combined mass of water found on, under, and
above the surface of a planet, minor planet or natural satellite.
Lithosphere- is the rigid, outermost shell of a terrestrial-type planet, or
natural satellite, that is defined by its rigid mechanical properties.
The environmental pollutions- it is a contamination of environment with
harmful wastes mainly arising from certain activites.
1. Natural pollution- is a pollutant created by substances of natural origin such
as volcanic dust, sea salt particles, photochemically formed ozone, and
products of forest fibres, among others.

2. Man-made pollution- Man-made pollutants can threaten human health
and compromise the natural ecosystem and environment. Man-made
pollution is generally a byproduct of human actions such as consumption,
waste disposal, industrial production, transportation and energy generation.
Stockholm Convention on Persistent Organic Pollutants is an
international environmental treaty that aims to eliminate or restrict the
production and use of persistent organic pollutants. The Stockholm
Convention, which currently regulates 23 POPs, requires parties to adopt a
range of control measures to reduce and, where feasible, eliminate the
release of POPs. For intentionally produced POPs, parties must prohibit or
restrict their production and use, subject to certain exempt ions such as the
continued use of DDT. The Stockholm Convention also requires parties to
restrict trade in such substances. For unintentionally produced POPs, the
Stockholm Convention requires countries to develop national action plans to
address releases and to apply "Best Available Techniques" to control them.
The Stockholm Convention also aims to ensure the sound management of
stockpiles and wastes that contain POPs.
Rotterdam Convention promotes open exchange of information and
calls on exporters of hazardous chemicals to use proper labelling, include
directions on safe handling, and inform purchasers of any known restriction or
bans. These international treaty for the conservation and sustainable
utilization of wetlands, recognizing the fundamental ecological functions of
wetlands and their economic, cultural, scientific, and recreational value.
The Basel Convention on the control of transboundary movements of
hazardous wastes and their disposal. Minimize the amount and toxicity of

wastes generated, to ensure their environmentally sound management as
closely as possible to the source of generation, and to assist LDC in
environmentally sound management of the hazardous and other wastes they
generate.
The Kyoto Protocol from japan is an international agreement linked to
the United Nations Framework Convention on Climate Change,
which commits its Parties by setting internationally binding emission reduction
targets. Recognizing that developed countries are principally responsible for
the current high levels of Greenhouse Gas emissions in the atmosphere as a
result of more than 150 years of industrial activity.
The Montreal Protocol does not address HFC (Hybrid fiber-coaxial), but
these substances figure in the basket of six greenhouse gases under the Kyot o
Protocol. Developed countries following the Kyoto Protocol report their HFC
emission data to UNFCCC.
The Montreal Protocol on substances that deplete the Ozone layer is
an international treaty designed to protect the ozone layer by phasing out
the production of numerous substances that are responsible for ozone
depletion.
The Nasty 9
1. Pentabromodiphenyl
This PBDE congener, sometimes referred to as ―penta,‖ was used as a
flame-retardant in foam upholstery and furnishing. It was first banned in
Germany, Norway and Sweden in the 1980s and 1990s, then in the
Europe Union in 2003. The last U.S. manufacturer stopped producing
the chemical in 2005, and the Environmental Protection Agency
subsequently banned its production in the U.S. It is still manufactured
elsewhere, primarily in China, and can be imported to the U.S. Maine

and Washington have banned it and nine other states have proposed
bans.
The chemical may cause a range of health problems, including liver
disease and reproductive and developmental problems. It has been
found in human breast milk.
2. Octabromodiphenyl
Like its sister ―penta‖ this polybrominated diphenyl ether, or PBDE, has
been linked to health issues and has largely been phased out in
developed nations. It used in conjunction with antimony trioxide as a
flame retardant in the housings of electrical and electronic equipment,
mainly in the plastic acrylonitrile butadiene styrene, but also in high
impact polystyrene, polybutylene
terephthalate and polyamides. Typically 12–15% of the weight of the
final product will consist of octabromodiphenyl.
3. Chlordecone
This insecticide, also known as Kepone, was used until 1978 in the
United States on tobacco, ornamental shrubs, bananas and citrus
trees, and in ant and roach traps. It is chemically almost identical to
Mirex, which was one of the original ―Dirty Dozen‖ banned by the
treaty.
Workers using chlordecone suffered damage to the nervous system,
skin, liver and male reproductive system. It may still be in use in
developing nations, despite its being banned in the industrialized world.
4. Lindane
An agricultural insecticide also used to treat head lice and scabies in
people, lindane has been banned in 50 nations because the
organochlorine pesticide can attack the nervous system. In t he United

States, it was used until 2007 on farms, and it is still used as a ―second-
line‖ treatment for head lice when other treatments fail.
Additionally, because Lindane is the only useful product in a family of
chemicals generated to produce the pesticide, there is persistent
chemical waste created by the process. For every ton of Lindane
produced, six to 10 tons of waste are produced.
5. Alpha-hexachlorocyclohexane
One of the persistent chemical waste products produced by making
Lindane, alpha-hexachlorocyclohexane may cause cancer and liver
or kidney problems.
6. Beta-hexachlorocyclohexane
Another of the persistent chemical waste products produced by
making Lindane, beta-hexachlorocyclohexane may cause cancer
and reproductive problems.
7. PFOS (Perfluorooctanesulfonic acid)
The company 3M used PFOS to make Scotchgard fabric and other
stain-resistant products until 2002. The chemical is also used in a
number of industrial processes. It is found in the bodies of people
around the world, and in relatively high concentrations in Arctic wildlife
— reflecting the global transport of persistent chemicals like these.
Unlike the other chemicals on the ―nasty nine‖ list, PFOS will have its use
restricted, not banned.
8. Hexabromobiphenyl
A polybrominated biphenyl, or PBB, hexabromobiphenyl is a flame
retardant that has been linked to a range of health problems, including
weight loss, skin disorders, nervous and immune systems effects, and

effects on the liver, kidneys, and thyroid gland. While it is no longer
used in developed nations, it may still be in use in developing nation.
9. Pentachlorobenzene
Used in the manufacture of an insecticide, and as a flame retardant,
Pentachlorobenzene may damage the nervous and reproductive
systems, as well as the liver and kidneys. It is also used as a head lice
treatment and can be found in the waste streams of some paper mills,
petroleum refineries, sewage treatment plants and incinerators.
Environmental Working Group released Dirty Dozen list and it serves as a solid
reminder that we still have a lot of work to do when it comes to cleaning up
the food system. This year, the report found that almost 70 percent of non-
organic samples tested positive for at least one pesticide. (In many cases, the
numbers were much higher.) A single strawberry sample harbored 22
different pesticide and pesticide breakdown residues. Polychlorinated
biphenyls were once widely deployed as dielectric and coolant fluids in
electrical apparatus, carbonless copy paper and in heat transfer fluids.
Philippines5 Environmental Laws
1. REPUBLIC ACT 9003 ECOLOGICAL SOLID WASTE MANAGEMENT ACT OF
2000
In partnership with stakeholders, the law aims to adopt a systematic,
comprehensive and ecological solid waste management program that shall
ensure the protection of public health and environment. The law ensures
proper segregation, collection, storage, treatment and disposal of solid waste
through the formulation and adaptation of best eco-waste products.
2. REPUBLIC ACT 9275 PHILIPPINE CLEAN WATER ACT OF 2004
The law aims to protect the country's water bodies from pollution from land-
based sources (industries and commercial establishments, agriculture and
community/household activities). It provides for comprehensive and

integrated strategy to prevent and minimize pollution through a multi-sectoral
and participatory approach involving all the stakeholders.
3. REPUBLIC ACT 8749 PHILIPPINE CLEAN AIR ACT OF 1999
The law aims to achieve and maintain clean air t hat meets the National Air
Quality guideline values for criteria pollutants, throughout the Philippines,
while minimizing the possible associated impacts to the economy.
4. REPUBLIC ACT 6969 TOXIC SUBSTANCES, HAZARDOUS AND NUCLEAR
WASTE CONTROL ACT OF 1990
The law aims to regulate restrict or prohibit the importation, manufacture,
processing, sale, distribution, use and disposal of chemical substances and
mixtures the present unreasonable risk to human health. It likewise prohibits
the entry, even in transit, of hazardous and nuclear wastes and their disposal
into the Philippine territorial limits for whatever purpose; and to provide
advancement and facilitate research and studies on toxic chemicals.
5. PRESIDENTIAL DECREE 1586 ENVIRONMENTAL IMPACT STATEMENT (EIS)
STATEMENT OF 1978
The Environment Impact Assessment System was formally established in 1978
with the enactment of Presidential Decree no. 1586 to facilitate the
attainment and maintenance of rational and orderly balance between
socio-economic development and environmental protection.

Cover
(Chemistry of the Atmossphere)
THE CHEMISTRY
OF THE
ATMOSTPHERE

Earth’s Atmosphere
The Atmosphere is a mixture of nitrogen (78%), oxygen (21%), and other
gases (1%) that surrounds Earth. High above the planet, the atmosphere
becomes thinner until it gradually reaches space. It is divided into five layers,
commonly known as Exosphere, Thermosphere, Mesosphere, Stratosphere,
and the Troposphere. Most of the weather and clouds are found in the first
layer.
The Atmosphere is an important part of what makes Earth livable. It
blocks some of the Sun's dangerous rays from reaching Earth. It traps heat,
making Earth a comfortable temperature. And the oxygen within our
atmosphere is essential for life.
Over the past century, greenhouse gases and other air pollutants
released into the atmosphere have been causing big changes like global
warming, ozone holes, and acid rain.
Gases in Earth's Atmosphere
Nitrogen and oxygen are by far the most common; dry air is composed
of about 78% nitrogen (N2) and about 21% oxygen (O2). Argon, carbon

dioxide (CO2), and many other gases are also present in much lower
amounts; each makes up less than 1% of the atmosphere's mixture of gases.
The atmosphere also includes water vapor. The amount of water vapor
present varies a lot, but on average is around 1%. There are also many small
particles - solids and liquids - "floating" in the atmosphere. These particles,
which scientists call "aerosols", include dust, spores and pollen, salt from sea
spray, volcanic ash, smoke, and more.
Layers of the Atmosphere
 Troposphere
o The troposphere is
the first layer above
the surface and
contains half of the
Earth's atmosphere.

Weather occurs in this layer. The troposphere is the lowest
layer of Earth's atmosphere. The troposphere starts at
Earth's surface and goes up to a height of 7 to 20 km (4 to
12 miles, or 23,000 to 65,000 feet) above sea level. Most of
the mass (about 75-80%) of the atmosphere is in the
troposphere. Air is warmest at the bottom of the
troposphere near ground level. Air pressure and the
density of the air are also less at high altitudes.
o The troposphere is heated from below. Sunlight warms the
ground or ocean, which in turn radiates the heat into the
air right above it. This warm air tends to rise. That keeps the
air in the troposphere "stirred up". Air also gets 'thinner' as
you go higher up. That's why mountain climbers sometimes
need bottled oxygen to breathe.
o The boundary between the top of the troposphere and
the stratosphere is called the t ropopause. The height of the
t ropopause depends on latitude, season, and whether it is
day or night. Near the equator, the t ropopause is about 20
km (12 miles or 65,000 feet) above sea level. In winter near
the poles the t ropopause is much lower. It is about 7 km (4
miles or 23,000 feet) high. The jet stream is just below the
t ropopause.
 Stratosphere
o Many jet aircrafts fly in the stratosphere because it is very
s
t
a
b
l
e
.

Also, the ozone layer absorbs harmful rays from the Sun.
The top of the stratosphere occurs at 50 km (31 miles)
altitude. The boundary between the stratosphere and the
mesosphere above is called the stratopause. The altitude
of the bottom of the stratosphere varies with latitude and
with the seasons, occurring between about 8 and 16 km (5
and 10 miles, or 26,000 to 53,000 feet). The bottom of the
stratosphere is around 16 km (10 miles or 53,000 feet)
above Earth's surface near the equator, around 10 km (6
miles) at mid-latitudes, and around 8 km (5 miles) near the
poles. It is slightly lower in winter at mid- and high-latitudes,
and slightly higher in the summer.
o Ozone, an unusual type of oxygen molecule that is
relatively abundant in the stratosphere, heats this layer as it
absorbs energy from incoming ultraviolet radiation from
the Sun. Temperatures rise as one moves upward through
the stratosphere. This is exactly the opposite of the
behavior in the troposphere in which we live, where
temperatures drop with increasing altitude.
o The stratosphere is very dry; air there contains little water
vapor. Because of this, few clouds are found in this layer;
almost all clouds occur in the lower, more humid
troposphere. Polar stratospheric clouds (PSCs) are the
exception.
PSCs appear
in the lower
stratosphere
near the
poles in
winter. They
are found at

altitudes of 15 to 25 km (9.3 to 15.5 miles) and form only
when temperatures at those heights dip below -78° C. They
appear to help cause the formation of the infamous holes
in the ozone layer by "encouraging" certain chemical
reactions that destroy ozone. PSCs are also called
nacreous clouds.
o A rare type of electrical discharge, somewhat akin to
lightning, occurs in the stratosphere. These "blue jets"
appear above thunderstorms, and extend from the
bottom of the stratosphere up to altitudes of 40 or 50 km
(25 to 31 miles).
 Mesosphere
o Meteors or rock fragments burn up in the mesosphere. The
mesosphere starts at 50 km (31 miles) above Earth's surface
and goes up to 85 km (53 miles) high.
o As you get higher up in the mesosphere, the temperature
gets colder.
The top of the
mesosphere is
the coldest
part of Earth's
atmosphere.
The
temperature
there is around
-90° C (-130° F)! The mesopause is the boundary between
the mesosphere and
the thermosphere
above it.

o Scientists know less about the mesosphere than about
other layers of the atmosphere. The mesosphere is hard to
study. Weather balloons and jet planes cannot fly high
enough to reach the mesosphere. Most meteors from
space burn up in this layer. A special type of clouds, called
"noctilucent clouds", sometimes forms in the mesosphere
near the North and South Poles. These clouds are strange
because they form much, much higher up than any other
type of cloud. There are also odd types of lightning in the
mesosphere. These types of lightning, called "sprites" and
"ELVES", appear dozens of miles above thunderclouds in
the troposphere below.
 Themosphere
o The thermosphere is a layer with auroras. It is also where
the space shuttle orbits. Temperatures climb sharply in the
lower thermosphere (below 200 to 300 km altitude), then
level off and hold fairly steady with increasing altitude
above that height. Solar activity strongly influences
temperature in the thermosphere. The thermosphere is
typically about 200° C (360° F) hotter in the daytime than
at night, and roughly 500° C (900° F) hotter when the Sun is
very active than at other times. Temperatures in the upper
thermosphere can range from about 500° C (932° F) to
2,000° C (3,632° F) or higher.
o Although the thermosphere is considered part of Earth's
atmosphere, the air density is so low in this layer that most
of the thermosphere is what we normally think of as outer
space. In fact, the most common definition says that
space begins at an altitude of 100 km (62 miles), slightly
above the mesopause at the bottom of the thermosphere.

The space shuttle and the International Space Station both
orbit Earth within the thermosphere.
o High-energy solar photons also tear electrons away from
gas particles in the thermosphere, creating electrically-
charged ions of atoms and molecules. Earth's ionosphere,
composed of several regions of such ionized particles in
the atmosphere, overlaps with and shares the same space
with the electrically neutral thermosphere.
 The Ionosphere s a layer of the earth's atmosphere
that is weakly ionized, and thus conducts electricity.
It is located approximately in the same region as the
top half of the mesosphere and the entire
thermosphere in the upper atmosphere, from about
40 mi (60 km), continuing upward to the
magnetosphere.
o The Aurora (the Southern and Northern Lights) primarily
occurs in the thermosphere. Charged particles (electrons,
p
r
o
t
o
n
s
,
a
nd other ions) from space collide with atoms and
molecules in the thermosphere at high latitudes, exciting
them into higher energy states. Those atoms and

molecules shed this excess energy by emitting photons of
light, which we see as colorful Auroral displays.
 Exosphere
o The atmosphere merges into space in the extremely thin
exosphere. This is the upper limit of our atmosphere. Very
high up, the Earth's atmosphere becomes very thin. The
exosphere is the outermost layer of our atmosphere. ―Exo‖
means outside and is the same prefix used to describe
insects like grasshoppers that have a hard shell or
―exoskeleton‖ on
the outside of their
body.
o The exosphere is the
very edge of our
atmosphere. This
layer separates the
rest of the atmosphere from outer space. It‘s about 6,200
miles (10,000 kilometers) thick. That‘s almost as wide as
Earth itself. The exosphere is really, really big. That means
that to get to outer space, you have to be really far from
Earth.
o The exosphere has gases like hydrogen and helium, but
they are very spread out. There is a lot of empty space in
between. There is no air to breathe, and it‘s very cold.
All of these layers, the most important layer of the atmosphere is the
troposphere it is protected from the hard ultraviolet radiation of the Sun by
the higher layers of the atmosphere, namely by the stratospheric ozone layer.
Because of this protection, many molecules are more stable in the
troposphere then elsewhere in the atmosphere. This protection makes life
possible on Earth. Carbon dioxide has a very long life span in the atmosphere
(several centuries). The presence of carbon dioxide is strongly linked to life on

Earth. CO2 is necessary for plant growth, since the carbon in animals and
plants originates exclusively from atmospheric CO2.
WEATHER OF ATMOSPHERE
Weather- is the state of the atmosphere at a given time and place.
Troposphere- The lowest layer of the atmosphere. The troposphere is heated
from below. Sunlight warms the ground or ocean, which in turn radiates the
heat into the air right above it. This warm air tends to rise. That keeps the air in
the troposphere "stirred up". The top of the troposphere is quite cold.
Weather describe in many variety of ways:
1. Air
TEMPERATURE- The real definition of temperature is the measure of the
average speed of air molecules. Temperature is measured in degrees by
using a thermometer. Even though temperature changes every day and
every season, the Earth's temperature is always in the right range to
support life.The temperature of the air depends on the temperature of the
surface directly below
PRESSURE- is an idea scientists use to describe how gases and liquids
"push" on things. The atmosphere has pressure. Atmospheric pressure is not
always the same. If a low pressure system or a high pressure system is passing
over your house, that will change the atmospheric pressure. Air pressure also

changes as you go up! The air pressure in Earth's atmosphere is pretty strong
when you are near sea level. When you go higher up, in an airplane or to the
top of a mountain, there is less pressure.
2. PRECIPITATION- (pre-sip-uh-tay-shun) is any form of water that falls to
the Earth's surface. Different forms of precipitation
include drizzle, rain, hail, snow, sleet, and freezing rain. Precipitation is
important because it helps maintain the atmospheric balance. Without
precipitation, all of the land on the planet would be desert . Precipitation can
also be damaging. Too much rain and snow can cause severe flooding and
lots of traffic accidents.
3. WIND- is moving air. Warm air rises, and cool air comes in to take its
place. This movement creates different pressures in the atmosphere which
creates the winds around the globe. Since the Earth spins, the winds try to
move to the right in the Northern Hemisphere, and to the left in the Southern
Hemisphere. This is called the Coriolis Effect.
4. TYPES OF CLOUD
CUMULUS CLOUDS-have sharp outlines and a flat base. Cumulus clouds
generally have a base height of 1000m and a width of 1km. Cumulus clouds
can be associated with good or bad weather. Cumulus humilis clouds are
associated with fair weather.
CIRRUS- Cirrus clouds are the most common of the High Cloud (5000-
13000m) group. They are composed entirely of ice and consist of long, thin,
wispy streamers. They are commonly known as "mare's tails" because of their
appearance. Cirrus clouds are usually white and predict fair weather.
CUMULONIMBUS- Cumulonimbus clouds belong to the Clouds with
Vertical Growth group. They are generally known as thunderstorm clouds.
Cumulonimbus clouds are associated with heavy rain, snow, hail, lightning,
and tornadoes.
STRATUS- Stratus clouds belong to the Low Cloud (surface-2000m up)
group. They are uniform gray in color and can cover most or all of the sky.
Stratus clouds can look like a fog that doesn't reach the ground.
LENTICULAR- Lenticular clouds form on the downwind side of
mountains. Wind blows most types of clouds across the sky, but lenticular
clouds seem to stay in one place. Air moves up and over a mountain, and at

the point where the air goes past the mountaintop the lenticular cloud forms,
and then the air evaporates on the side farther away from the mountains.

Weather changes each day because the air in our atmosphere is
always moving. While weather can change rapidly, climate changes slowly.
Over the past century, greenhouse gases and other air pollutants
released into the atmosphere have been causing big changes like global
warming, ozone holes, and acid rain.
CLIMATE CHANGE
Warm near the equator and cold at the poles. The scientific
consensus is that climate is warming as a result of the addition of heat -
trapping greenhouse gases. Climate has cooled and warmed
throughout Earth history for various reasons. Rapid warming like we see
today is unusual in the history of our planet.
POLAR ATMOSPHERE
There are some unique phenomena that happen in the atmosphere
that is above the Earth's polar regions.
AURORA- High in the thermosphere layer of Earth's atmosphere,
energized particles that come from the Sun follow Earth's magnetic field lines
toward the Poles. The gases of the upper atmosphere light up with the added
energy. The display is called the aurora. It can only be seen at high latitudes
and is called the Northern Lights in the Northern Hemisphere and the
Southern Lights in the Southern Hemisphere.
NOCTILUCENT CLOUDS- In the mesosphere layer of Earth‘s atmosphere,
below the thermosphere and above the stratosphere, noctilucent clouds
form in the polar regions. This is much higher in the atmosphere than typical
clouds, but noctilucent clouds are not typical clouds. The word noctilucent
means to glow, and these clouds do glow blue in color when they are lit from
below by the setting Sun.
LESS OZONE- The ozone layer, located in the stratosphere layer of the
atmosphere, shields our planet from harmful UV radiation. Most of the ozone
destruction happened in the part of the stratosphere that is over Earth‘s polar
regions.
COLD WEATHER- Less solar energy gets to the poles making for lots of
cold weather. However, even though both poles get the same amount of

sunlight, the North Pole is less cold and has different weather than the South
Pole.
ATMOSPHERIC OPTICS
Atmospheric Optics shows us how light behaves as it passes through the
atmosphere.
MECHANISMS
REFLECTION- Is the change in direction of a wave front at
an interface between two different media so that the wave front returns into
the medium from which it originated.
REFRACTION- Refraction is the bending of light (it also happens with sound,
water and other waves) as it passes from one transparent substance into
another. This bending by refraction makes it possible for us to have lenses,
magnifying glasses, prisms and rainbows.
SCATTERING- A change in the direction of motion of a particle because of
the collision with another particle. As defined in physics, a collision can occur
between particles that repel one another, such as two positive (or negative)
ions, and need not involve direct physical contact of the particles.
DIFFRACTION- Is the slight bending of light as it passes around the edge of an
object. The amount of bending depends on the relative size of the
wavelength of light to the size of the opening.
Why the Sky is Blue?
The atmosphere is made up of mostly nitrogen and oxygen. They are
selective scatters, meaning they scatter short wavelengths best (violet, blue,
and green). Our eyes are most sensitive to blue light, so the sky appears blue
to us!
Why do clouds look white and sometimes dark?
Water vapors (clouds) scatter all wavelengths equally. The result is
white. When clouds are thick (like thunderclouds) they absorb much of the
light. Water drops also tend to absorb light. The result is a darker cloud.
The Green Flash
Green flash is an atmospheric phenomenon observed occasionally at
sunset. Remember at sunset that the light travels through a much greater
amount of atmosphere—this bends the light from the setting sun so that we
see the sun for a short while after it has actually set. Blue light bends the most
so we should see some blue light at the top of the setting sun. However

because the blue light is scattered out the most very little reaches us and we
see green light instead.
Crepuscular Rays (Jacobs Ladder)
Particles in the sky (dust, water droplets, or haze) scatter light in their path
making that region appear bright with rays.
Halo around the sun
Light is refracted by tiny suspended ice crystals.
Rainbow
Sunlight hitting a raindrop in the atmosphere is refracted on the surface
of the raindrop and enters the droplet. Once refraction occurs, the light
breaks up into seven colors inside the raindrop; it is then reflected to the other
side of the raindrop after traveling inside it. When the light in the raindrop
refracts, the spectrum forms to make the 7 colors of the rainbow appear.
During reflection, the angle (of reflection) is equal to the angle of incidence;
this means that reflected light travels along a set path and maintains the
difference of the refraction angle. A rainbow is a bunch of raindrops hanging
in the atmosphere that divide the sunlight into 7 colors, like a prism.
AIR POLLUTION
Air pollution refers to the release of pollutants into the air that are detrimental
to human health and the planet as a whole.
COMMON EXAMPLES OF AIR POLLUTION
Smog- A kind of air pollution, originally named for the mixture of smoke and
fog in the air.
Acid rain - Is a general term used to describe different kinds of acidic air
pollution such as sulfur dioxide and nitrogen oxide. Can have harmful impacts
on the ecosystems in the environment. It acidifies the soil and water where it
falls, damaging or killing plants and animals.
Carbon Monoxide- An odorless, colorless, tasteless, and toxic air pollutant.
Produced in the incomplete combustion of carbon containing fuels, such as
gasoline, natural gas, oil, coal and wood.
Tropospheric Ozone- Ozone is released naturally in the troposphere by plants
and soil. These are such small amounts that they are not harmful to the health
of humans, animals or the environment.
NATURAL VS. MAN-MADE
Natural

Natural processes impacting the atmosphere include volcanoes, biological
decay, and dust storms. Plants, trees, and grass release volatile organic
compounds (VOCs), such as methane, into the air.
Man-Made
Human-made pollutants include carbon monoxide, sulfur dioxide, VOCs, and
nitrogen oxides. The largest source of human-made pollution is the burning of
fossil fuels, including coal, oil, and gas, in our homes, factories, and cars.
PRIMARY OR SECONDARY AIR POLLUTION
Primary pollution is put directly to the air, such as smoke and car exhausts.
Secondary pollution forms in the air when chemical reactions changes
primary pollutants. The formation of tropospheric ozone is an example of
secondary air pollution.
EFFECTS OF AIR POLLUTION
1. Respiratory and heart problems: The effects of Air pollution are alarming.
They are known to create several respiratory and heart conditions along with
Cancer, among other threats to the body.
2. Global warming: With increased temperatures world wide, increase in sea
levels and melting of ice from colder regions and icebergs, displacement
and loss of habitat have already signaled an impending disaster if actions for
preservation and normalization aren‘t undertaken soon.
3. Eutrophication: Eutrophication is a condition where high amount of
nitrogen present in some pollutants gets developed on sea‘s surface and
turns itself into algae and adversely affect fish, plants and animal species.
4. Effect on Wildlife: Toxic chemicals present in the air can force wildlife
species to move to new place and change their habitat.
5. Depletion of Ozone layer: Earth‘s ozone layer is depleting due to the
presence of chlorofluorocarbons, hydro chlorofluorocarbons in the
atmosphere. As ozone layer will go thin, it will emit harmful rays back on earth
and can cause skin and eye related problems.

OZONE HOLES
Ozone depletion, gradual thinning of Earth‘s ozone layer in the
upper atmosphere caused by the release of
chemical compounds containing gaseous chlorine or bromine from industry
and other human activities.
OZONE LAYER
The ozone layer is a range of altitudes in Earth's stratosphere which has a
higher concentration of ozone molecules. Ozone is an unusual type
of oxygen molecule. It is created when high-energy ultraviolet light from the
Sun strikes a normal oxygen molecule.
OZONE IN THE STRATOSPHERE
Ozone in the stratosphere protects us from ultraviolet radiation in sunlight. The
ozone layer is sort of like sunscreen for planet Earth. It absorbs most of the
incoming UV "light" before it reaches the ground.
Various chemicals that humans release into the atmosphere can destroy
ozone in the stratosphere. That is a problem since it allows more UV radiation
to make it to the surface. In the 1980s, scientists noticed that the ozone layer
was thinning. They also noticed huge holes in the ozone layer, especially over
Antarctica. They convinced people and governments around the world to
reduce emissions of ozone-destroying chemicals. They hope the ozone layer
will heal itself over time.

Cover
(The Chemistry of Water)
THE CHEMISTRY OF
WATER

Introduction
The chemistry of water deals with the fundamental chemical property and
information about water. Water is very important resource of life and life is not
possible without this. As we dig deeper, Hydrosphere is the total water system
of planet earth and within earth, it undergoes hydrospheric processes. Waters
containing calcium and magnesium is called hard water. Soft water has only
ion – sodium. In part of hard water, temporary hardness is the amount of
metal ions removed from boiling and permanent hardness is the amount of
metal ions that remained. Hard water can be converted to soft water
through ion exchange. Hard water is good for drinking while soft water is
suitable for household chores. Water is seen as the source of life. Many living
organisms live in water and balance it to survive. There are some essential
electrolytes to support human life. 70 percent of human body weight is water
which contributed to its major compartments. Electrolytes can be found in
sports drink to replaced the diminished electrolytes during activities.
V. What is water?
Water is the most important resource. Without water life is not
possible. From a chemical point of view, water, H2O, is a pure
compound, but in reality, you seldom drink, see, touch or use pure
water. Water from various sources contains dissolved gases,
minerals, organic and inorganic substances.
Figure no.1 Water, or H2O
VI. THE HYDROSPHERE

The total water system surrounding the Planet Earth is called
Hydrosphere.
Includes: Freshwater system, oceans, atmosphere vapor, and
biological waters.
Oceans 97%
Fresh water 1%
Ice caps and glaciers 2-3%
Hydrospheric processes are steps by which water cycles on the
planet Earth. These processes include sublimation of ice,
evaporation of liquid, transportation of moisture by air, rain, snow,
river, lake, and ocean currents. All these processes are related to
the physical and chemical properties of water, and many
government agencies are set up to study and record phenomena
related to them. The study of these processes is called hydrology.
Figure no.2 Hydrospheric process
Among the planets, Earth is the only one in which there are solid,
liquid and gaseous waters. Water is the most abundant substance in
the biosphere of Earth. Groundwater is an important part of the
water system. When vapor is cooled, clouds and rain develop.
Some of the rain percolate through the soil and into the underlying
rocks. The water in the rocks is groundwater, which moves slowly. A
body of rock, which contains appreciable quantities of water, is
called an aquifer.

VII. HARD WATER
Waters containing Ca2+ and Mg2+ ions are usually called hard
water Hard waters need to be treated for the following applications.
• Heat transfer carrier in boilers and in cooling systems
• Solvents and reagents in industrial chemical applications
• Domestic water for washing and cleaning
Soft water is treated water in which the only ion is sodium. Soft
water is suitable for household chores because its ion has a positive
reaction towards any cleaning detergent. While hard water is less
effective in detergents due to its reaction to the magnesium and
calcium.
VIII. TEMPORARY VS. PERMANENT HARD WATER
Water containing Ca2+, Mg2+ and CO32- ions is called temporary
hard water, because the hardness can be removed by boiling.
Boiling drives the reverse reaction, causing deposit in pipes and
scales in boilers. The deposits lower the efficiency of heat transfer in
boilers, and diminish flow rates of water in pipes. Thus, temporary
hard water has to be softened before it enters the boiler, hot -water
tank, or a cooling system. The amount of metal ions that can be
removed by boiling is called temporary hardness
Amount of metal ions that cannot be removed by boiling is
called permanent hardness. Total hardness is the sum of temporary
hardness and permanent hardness.
IX. ION EXCHANGE TO CONVERT HARD WATER TO SOFT WATER
The exchange takes place by passing hard water over man-
made ion exchange resin beads/zeolite, in a suitable pressure vessel
tank. The resin in most modern softeners (polystyrene divinyl
benzene) consists of millions of tiny plastic beads, all of which are
negatively charged exchange sites. The ions considered in this
process (calcium, magnesium and sodium) are all positively
charged ions. When the resin is in the base state, the negatively
charged resin beads hold positively charged sodium ions. As the
calcium and magnesium contact the resin beads in their travel

through the resin tank, they displace the sodium ions from the
exchange sites.
Figure no.3 Ion exchange
X. HOW LIFE STARTED
Water dissolves or emulsifies other life-supporting substances and
transport them to intercellular and intracellular fluids. It is also a
medium in which reactions take place. Reactions provide energy
(non-matter) for living. Energy causes changes, and manifestation
of changes is at least related to, if not t he whole, life. An organized
and systematized set of reactions is essential in each life.
There are strong evidences that life on earth appeared in a body of
water. Only the planet Earth has three states of water, and it offers a
suitable environment for life to begin, among all nine solar planets.
Since all life forms involve water. Water is seen as the source, matrix,
and mother of life. Water is important, because water is required for
life, and some people even consider water as life blood.
XI. BALANCING WATER IN BIO-SYSTEMS
Many living organisms live their lives entirely in water. Aquatic
living organisms extract nutrients from water, yet maintaining a
balance of electrolyte and nourishment concentration in their cells.
For living things not living in water, they extract water from their
environment by whatever mechanism they can. Cells in their body
are surrounded by body fluid, and all cells maintain constant
concentrations of electrolytes, neutrints, and metabolites. The

Cover (The Chemistry of Engineering Materials

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Cover (The Chemistry of Engineering Materials